In many instances, workers are required to climb trees, utility poles, or other vertical structures. For example, utility workers are frequently called upon to remove fallen limbs and trim trees away from power lines. Similarly, tree surgeons shape trees and cut dead limbs. These jobs often require the use of a gas-powered chainsaw or other tool and are commonly performed while a worker is working aloft.
Climbing and remaining stationary on a structure with a chainsaw is a difficult task. Numerous retaining devices have been developed to prevent a worker from accidentally dropping the chainsaw. These devices keep the chainsaw attached to the worker while allowing the worker to perform a job with unencumbered use of the chainsaw. Further, if the chainsaw accidentally falls, these devices allow the saw to reach a level below the worker's feet, but above the ground. Thus, the risk of damage to the chainsaw or injury to a bystander on the ground is minimized.
Many of the aforementioned retaining devices are lanyards or cords that incorporate a break-away component (e.g., swage) into their designs. One such device, entitled SNAP & SNAP CHAIN SAW LANYARD, is illustrated in a catalog by American Arborist Suppliers, Inc., as Catalog No. S190196-00. The devices comprise break-away or tear-away components that separate in response to a predetermined force. For example, when a chainsaw is dropped, an impact load (i.e., the weight of the falling chainsaw) acts on the component. Tensile forces are exerted on the component, causing it to shear or break. In order for this shearing action to occur, the tensile forces obviously must be greater than the predetermined failure point of the component. Unfortunately, the force exerted on a worker during the shearing of the component could be sufficient to dislodge the worker or cause severe injury while the worker is attached to the structure. Currently, chainsaw lanyards separate when sufficient force is applied to shear the break-away feature.
What is needed is a retaining lanyard that enables the chainsaw to tear away slowly while minimizing the force on the worker. In other words, a break-away mechanism is needed to provide a controlled tearing action over a predetermined distance when the chain saw is pinched in a falling limb.
The present invention provides such a device for use by a worker. It includes a tear-away component and a feature which minimizes the lanyard length when relaxed. The tear-away component is housed in a nylon sheath to protect the component from damage. The tear-away component is designed to separate with a force that, in general, can be withstood by the human body without a loss of balance. The novel device maintains attachment of a chainsaw to the worker and allows freedom of movement when cutting. There are numerous methods of attaching/detaching the chainsaw between a worker's fall protection belt and the novel tear-away retaining lanyard.
The lanyard construction consists of a nylon or polyester tubular web with an elastic cord center, capable of reducing its fully stretched length by one half. This feature aids in reducing the potential of entanglement when working aloft.
If the chainsaw gets caught in a falling limb while the worker is attached to the tree, the tear-away component will pull apart when an excessive force is applied. In the event that the tear-away component separates entirely, the chainsaw will be released from the worker and fall to the ground with the limb, allowing the worker to maintain his/her position within the structure.